Determinants of the knowledge of and attitude towards tuberculosis in Nigeria.

Globally, Nigeria had the fourth highest incidence of tuberculosis (TB) cases in 2009. Datasets of the 2008 Nigeria Demographic and Health Survey (NDHS) were used for examining factors associated with respondents' knowledge of and attitude towards TB in Nigeria. With the same age-group of males and females, the sample included 47,193 respondents aged 15-49 years. Factors associated with the knowledge of and attitude towards TB were examined against a set of individual-, household- and community-level variables, using multiple binary logistic regression analyses. Respondents who reported having ever heard of TB was 74.7%. Of those who ever heard of TB, 76.9% believed that TB can be cured, and 19.6% would want a family member's TB to be kept secret. Of those who ever heard of TB, 63.1% believed that TB was spread from person to person through the air by coughing or sneezing. Multivariate analysis indicated that the probability of having poor knowledge of and negative attitude towards TB was consistently significant among the poorest household (lowest wealth quintile), geopolitical regions (North Central), respondents with no schooling, non-working respondents, youngest age-group (15-19 years), and rural areas [adjusted odds ratios (AOR)=0.76, 95% CI 0.66-0.86 for respondents who had ever heard of TB; AOR=0.89, 95% CI 0.80-0.99 for respondents who had ever heard of TB and believed that TB can be cured; AOR=0.83, 95% CI 0.73-0.94 for those who had ever heard of TB and concealed the fact that a family member had TB; and AOR=0.88, 95% CI 0.78-0.99 for those who had ever heard of TB and believed TB was spread from person to person through the air by coughing or sneezing]. Efforts to improve the knowledge of and attitude towards TB in Nigeria should focus on the youngest age-group (15-19 years), the poorest households, and respondents with no schooling. Improving the knowledge and attitude of these groups of individuals may result in an increase in the number of people who will seek early treatment.


INTRODUCTION
TB remains a major public-health problem in many low-income and middle-income countries (1,2). In 1993, the World Health Organization (WHO) declared TB as a global health emergency (2,3). Since then, there has been an intensification of global efforts to control this disease. Reduction in the burden of TB has been a key priority of the Millennium Development Goal (MDG) 6 agenda Past studies indicated that patients in Nigeria did not often engage in adequate healthcare-seeking behaviour to reduce the incidence of infectious diseases, including TB, and this has been attributed to the lack of knowledge about the cause, transmission, and significant symptoms of the disease as well as negative social attitudes (10)(11)(12)(13). The burden of disease from TB is disproportionally high among individuals living in rural areas, those who live below the poverty line (13,14) as well as in economically-underprivileged countries, highlighting a strong association between poverty and TB (15).
A recent study conducted in Benin-City, Nigeria, indicated that TB awareness programme and knowledge of transmission of TB could increase case-detection rates (7), and individuals who acknowledged the severity of TB were more likely to stay healthy (16). Hence, understanding the factors associated with the knowledge of and attitude towards tuberculosis is considered the first step towards promoting healthcare-seeking behaviour in the community towards infectious diseases in Nigeria (17).
To the best of our knowledge, there has not been any reliable population-based study on the knowledge of and attitude towards TB in Nigeria. Thus, a more detailed understanding of the factors associated with the knowledge of and attitude towards TB is needed to support case detection and reduce TB-related morbidity in Nigeria. The purpose of the present study was to use data from the existing representative survey to identify factors associated with the knowledge of and attitude towards TB in Nigeria.

Ethical clearance
The DHS project sought and obtained necessary ethical approval from ethics committees in Nigeria before the survey was carried out. Informed consent was obtained from study participants before they were allowed to participate in the survey. The datasets used in this report were completely anonymous with regard to participants' identity.

MATERIALS AND METHODS
The present analysis was based on a publiclyavailable datasets that were collected for the 2008 Nigeria Demographic and Health Survey (NDHS) (18). The survey was conducted by the National Population Commission (19). The NDHS is a useful and valid source of information on the knowledge of and attitude towards TB from a nationallyrepresentative sample of households. The survey sample was selected in two stages. In the first stage, 886 clusters were selected from a list of enumeration areas (EAs) developed from census frame of the 2006 enumeration areas (18). In the second stage, a complete listing of households was carried out in each selected cluster. In total, 34,644 households were selected for the sample, of which 34,070 were successfully interviewed, yielding a response rate of 98%. There was no significant difference between response rates in rural and urban areas (18).
From the sampled households, 33,385 women aged 15-49 years (response rate 96.5%) and 15,486 men aged 15-59 years (response rate 92.6%) were interviewed using a questionnaire to collect data on the respondent's backgrounds, sociodemographic information for all persons usually residing in each household as well as an inventory of household facilities and assets. To answer our research question and ensure that the age-groups were the same for men and women, the current study reports on the 47,193 adults aged between 15 and 49 years.
The explanatory variables were classified into three levels: individual-, household economical-and community-level factors. Individual-level factors included: respondents' working status, education, age, religion, and marital status. Householdeconomical-level factors were household wealth index; respondents' literacy; access to television, magazines/newspapers and radio while community-level factors included type of residence, ethnicity, and geopolitical zones. Geopolitical zones were defined based on ethnic homogeneity of nearperfect political, administrative, and commercial city in Nigeria.
A wealth index was constructed from the data collected through the household questionnaire (20). Using this method recommended by the World Bank Poverty Network and United Nations Children's Fund (20), the data were divided into five categories. The lowest quintile-bottom 20% of the households-was referred to as the poorest households, and the highest quintile-top 20%-as the richest households.
In the remaining part of this paper, TB transmission outcome variables will be expressed as responses to these questions/statements: "Have you ever heard JHPN 522 of an illness called TB"; "Can TB be cured?"; "Would you want a family member's TB to be kept secret?"; "TB is spread through air when coughing or sneezing"; and "TB is spread through sharing utensils." These were expressed as dichotomous variables, with category 1 for 'yes' and category 0 for 'no'. These variables were examined against a set of independent variables (individual-level, household economical-and community-level) to determine factors associated with the knowledge of and attitude towards TB. Analyses were performed using Stata (version 12.0) (StataCorp, College Station, TX, USA). 'Svy' commands were employed to allow for adjustments for the cluster-sampling design and the calculation of standard errors. The Taylor series linearization method was used in the surveys when estimating confidence intervals around prevalence estimates of knowledge-and attitude-related questions concerning TB. Multivariate logistic regression was conducted to determine the factors significantly associated with the knowledge of and attitude towards TB. Odds ratios with 95% confidence intervals (CI) were calculated to assess the adjusted risk of independent variables with 95% CI, including 1.0 being regarded as a non-significant result.

Characteristics of the sample
As summarized in Table 1, majority of the respondents lived in rural areas (63.7%). Approximately 65% of the respondents were employed in the last 12 months, and 49.4% had attained secondary or higher level of education. Of the total respondents, 70.7% were female. The proportion of individuals who could not read a sentence was 46.3%, and about 24% of the respondents were from the North-West of the country. The majority of respondents were currently married, and 44.7% belonged to the Islamic faith.

Knowledge of and attitude towards TB: proportion of respondents
Of the total sample of 47,193 adults aged between 15 and 49 years from Nigeria, the proportion of individuals who had ever heard of an illness called TB was 74.7%. The proportion of individuals who reported that TB was curable was 76.9%; 19.6% of individuals reported that TB would be kept secret if a member of their family contracted it among those individuals who thought that TB could be spread from person to person, 63.1% thought that TB could be spread through the air when coughing or sneezing; 36.5% of individuals reported that TB could be spread through sharing utensils; 3.9% of respondents thought TB could be spread through touching a person with TB. The proportions of individuals who thought TB could be spread through food, sexual contact, and mosquito bites were 11%, 5.0%, and 0.8% respectively ( Table 2). Table 3 shows the prevalence estimates of TB transmission (for ever heard of TB, believed that TB can be cured, would want a family member's TB to be kept secret, and TB is spread through coughing or sneezing and sharing utensils) by selected individual-, household economical-and communitylevel characteristics. It was found that gender, age in categories, respondents' working status, marital status, frequency of listening to radio, frequency of reading, household wealth, literacy, place of residence, geopolitical zones, ethnicity, and religion were all significantly associated with ever heard of TB, would want a family member's TB to be kept secret, believed that TB can be cured, and TB is spread through coughing or sneezing. Table 3 indicates that gender, respondents' working status, marital status, frequency of listening to radio, frequency of reading newspapers or magazines, frequency of watching television, household wealth, educational status, literacy, place of residence, geopolitical zone, ethnicity, and religion were associated with the belief that TB is spread through coughing or sneezing, and TB is spread through sharing utensils.

Multivariate analysis
Adjusted odds ratios (AORs) were calculated to determine the strength of association between independent variables and ever heard of TB, believed that TB can be cured, and would want a family member's TB to be kept secret as presented in Table 4. Females were significantly less likely to report than male respondents that they had ever heard of TB and believed that TB was curable. Respondents aged between 15 and19 years and those who lived in rural areas were less likely to report that they had ever heard of TB, believed that TB could be cured, and would want a family member's TB to be kept secret compared to those of other agegroups and those who lived in urban areas.
Never-married respondents and those respondents who had limited access to the electronic media were significantly less likely to report that they ever heard of TB and believed that TB is curable. The poorest households (lowest wealth quintiles) were significantly less likely to have heard of TB and believed that TB could be cured than the richest households (highest wealth quintiles). Respondents working in the previous 12 months and those with primary, secondary or higher level of education were significantly more likely to have ever heard of TB, believed that TB was curable, and would want a family member's TB to be kept secret.
The Ekio ethno-linguistic group, when compared with respondents who lived in the other ethnolinguistic groups in Nigeria, were significantly less likely to have heard of TB, believed that TB is curable, and would want a family member's TB to be kept secret. Respondents who belonged to the Catholic faith were more likely to have ever heard of TB, believed that TB could be cured, and would want a family member's TB to be kept secret com- Adjusted odds ratios (AORs) of factors that were associated with the belief that TB is spread through coughing or sneezing and sharing utensils are shown in Table 5. Females were significantly less likely to report than males that TB is spread through coughing or sneezing and significantly more likely to report that TB is spread through sharing utensils. Respondents aged between 15 and 19 years were less likely to report that they believed TB is spread through coughing or sneezing and would significantly report that TB was spread through sharing utensils compared to those of other age-groups. Respondents who lived in rural areas were significantly less likely to report that they believed TB is spread through coughing or sneezing compared to those who lived in urban areas.
Non-literate respondents and those respondents who had limited access to the electronic media were significantly less likely to believe that TB is spread through coughing or sneezing and to report that TB is spread through sharing utensils compared to literate respondents and those respondents who had easy access to the electronic media. The poor-est households were less likely to believe that TB is spread through coughing or sneezing and to report that TB is spread through sharing utensils compared to the richest households. Respondents working in the previous 12 months and those with primary, secondary or higher levels of education were significantly more likely to believe that TB is spread through coughing or sneezing and to report that TB was spread through sharing utensils than their non-working and uneducated counterparts.
The Ekio ethno-linguistic group, when compared with respondents from other ethno-linguistic groups, were significantly less likely to believe that TB was spread through coughing or sneezing and that TB is spread through sharing cookingutensils. Respondents who belonged to the Catholic faith were more likely to believe that TB is spread through coughing or sneezing compared to those who were non-Catholic Christians and others practising religions, such as Hinduism, Judaism, Grail movement, and Hare Krishna.

DISCUSSION
The purpose of this study was to examine the prevalence of and factors associated with the knowledge of and attitude concerning TB in Nigeria. The study indicated that high proportions of respond-       ents were aware of TB and believed that TB is a curable infectious disease. This finding is in agreement with those from a recent study in India (21) and another community-based survey in Ethiopia (22), in which majority of participants in a survey were found to have heard about TB and believed that the disease is curable. Despite this fact, a significantly high number of respondents would conceal the fact that a family member had TB. This meant that most respondents exhibited an unfavourable attitude towards TB patients, which could potentially lead to a stigmatization of these patients. This finding is also consistent with a recent study in Ethiopia (22). Our study also found that a few respondents believed that TB could be spread through sexual contact, food, or a mosquito bite, and by touching a TB patient.
The study also revealed that majority of the respondents aged 15-49 years hinted they had heard of TB, and more than half of them had knowledge of the cure of TB. Less than half of the respondents had knowledge of TB being an airborne disease and that it could be transmitted from person to person during coughing or sneezing. These findings are broadly consistent with studies conducted in the Philippines, Ethiopia, China, and Viet Nam (13,17,23,24), which indicated that a large proportion of the population had heard of TB and also believed that TB is transmissible and curable. In another study on sandstone quarry workers in the desert parts of Rajasthan, other authors reported that a high percentage of the workers were aware that TB is a communicable disease (23).
Furthermore, our study indicated that male respondents were more aware of TB than their female counterparts. Also, compared to females, more males believed that TB could be transmitted from person to person through air during coughing or sneezing and that the disease is curable. These findings are broadly consistent with a study conducted by other authors (22) who stated that more females lacked knowledge about TB symptoms than males but females were more likely than males to seek healthcare relating to TB. Additionally, our findings are consistent with studies conducted in Sudan (25), India (21), and Ethiopia (22), which reported that the level of awareness among males about TB was significantly more than among females. The findings may also reflect differences in gender education in Nigeria where men are more likely to be educated than women (26).
The prevalence of each of the five outcome variables of interest (Table 3) was generally lower among non-literate respondents and higher among respondents with secondary or higher levels of education. Employed respondents and those who had access to the electronic media also showed a higher prevalence of each of the five outcome variables of interest. Our findings are consistent with studies by Okuonghae et al., Mweemba et al.,and Mushtaq et al. (7,27,28), which concluded that high rates of illiteracy, low educational status, and unemployment status were common among TB patients. Also, a study conducted in Nigeria (7) observed that the lack of any formal education and non-access to the electronic media (TV and radio) were among the strongest predictors of high rates of TB cases in Benin-City in Nigeria. This finding also agrees with the results from two separate studies in Pakistan and Iraq (28,29), which indicated that the media play a vital role in patients' knowledge about TB and, thus, highlight the need for TB health education programmes among non-literate households. The study in India (21) found only the radio, among the other media sources, to be associated with the correct knowledge of TB transmission.
This study showed a low prevalence of each of the five outcome variables of interest (Table 3) for rural and poor households. These findings are consistent with national household surveys conducted in the Philippines, Pakistan, and India (17,21,30), which indicated that higher knowledge about TB was observed among urban dwellers. This finding may reflect the fact that respondents who lived in rural areas and came from low socioeconomic backgrounds were more likely to feel embarrassed and stigmatized for having TB (28).
Results of our study showed that younger and unmarried respondents were less likely to report they had ever heard of TB and to report TB is spread through air during coughing or sneezing. A study in the Philippines (23) reported similar results. In Nigeria, as in most African countries, men and women eventually marry and, so, there is a strong link between age and marital status (31).
The prevalence of awareness about TB and the belief that TB is curable were found to be relatively lower among respondents from the North-Central geopolitical zone of Nigeria. Formal education might have played an important role in this finding as respondents from this zone had relatively lower levels of formal education compared to those from the other geopolitical zones of Nigeria (18). However, further research is needed to compare the prevalence of TB in each geopolitical region.
This study revealed that respondents who belonged to the Catholic faith reported a higher prevalence of each of the five outcome variables of interest (Table 3) compared to those from other religious denominations. These results may reflect the role of Roman Catholic Missionaries in building churches and hospitals to reduce the burden of the disease in Nigeria. For example, the Catholic church is one of the primary healthcare providers in Nigeria as they manage 31 TB screening and treatment centres across 16 states of the country (32).
A multiple binary logistic regression analysis method was used for showing that females, younger and never-married respondents were significantly associated with having ever heard of TB, reporting that TB is spread through air during coughing or sneezing and the belief that TB is curable. Respondents who watched television at least once a week or who did not watch television at all, poorest households as well as unemployed and uneducated respondents were also significantly associated with the outcome variables mentioned. Currentlymarried male respondents from rural areas, who were uneducated and unemployed and who watched television at least once a week or did not watch television at all, were associated with the report that they would keep a family member's TB secret and that TB is spread by sharing utensils. These results support similar findings that poverty, unemployment, no formal education, age, and gender were significantly associated with the knowledge of and attitude towards TB (11,23,27,29).

Strengths and limitations of the study
One limitation of this study is that it only reported a 'snapshot' of the frequency of people's knowledge of and attitude towards TB since it had a crosssectional design. Another limitation is that the study did not examine the relationship between HIV/AIDS and TB. Despite these limitations, the findings from this study would contribute to our understanding of the factors associated with the knowledge of and attitude towards TB, which may improve the quality and quantity of information dissemination about TB in Nigeria. Access to a large national survey, appropriate sampling method, and appropriate adjustment for sampling design, including sampling weight and a high response rate are important strengths of the survey.

Conclusions
Our findings indicate that majority of the households had basic knowledge about TB but females, 537 uneducated respondents, residents of poor households, and respondents who did not belong to the Catholic faith reported that they ever heard of TB, believed that TB could be cured, would want a family member's TB to be kept secret, and that TB is spread through coughing or sneezing and sharing utensils. The present study also showed that the literate people had a much better knowledge of and attitude towards TB than their non-literate counterparts. However, understanding of the factors associated with the knowledge of and attitude towards TB is considered the first stage of promoting healthcare-seeking behaviours, which may reduce the incidence of TB and will assist in the achievement of Millennium Development Goal 6. Finally, there is need for community mobilization and public education on TB in order to reduce the burden of TB in Nigeria.